The issue appears clearly in the log:
And indeed the terrain textures UUIDs are the ones listed there.
The bug is a race condition between the moment the textures start getting fetched by the viewer and the moment when the region sends the capabilities (URIs) to allow fetching them (and apparently, this region is especially slow at sending them)...
Fixed for tomorrow's release.
In the mean time and as a work-around, you may disable "SkipCachedTerrainTextures" by setting it to to FALSE (which sadly will likely cause the mini-map terrain textures to fail loading, sometimes) and instead of TPing away and back in to prime the cache with those terrain textures, you may open the "Region/estate" floater (ALT R or "World" - > "Region/estate") and from its "Ground textures" tab, click on the grey textures, and finally in the texture preview floaters that appear, click the exclamation mark button to force a reload of each texture.